Hearing Preservation and Facial Nerve Function Comparing the Middle Fossa Approach and the Retrosigmoid Approach for Removal of Vestibular Schwannomas

Introduction: Between 1995 and 2006, 454 acoustic neuromas were operated on at our institutions using either the middle fossa (n = 166) or the retrosigmoid approach (n = 156). Preoperatively, all patients had serviceable hearing and normal facial nerve function with the exception of 1 patient. The approach was selected primarily on the basis of the tumor extension toward the brainstem or the fundus of the internal auditory meatus. All procedures were performed using intraoperative monitoring of facial nerve and auditory function (ABR and EcoG). Tumor resection was carried out in all cases by two surgeons only.

Results: Complete tumor resection was achieved in 97% of the cases. There were 3 recurrences. Hearing preservation with some degree of residual hearing was achieved in 54% using the middle fossa approach and 32% using the retrosigmoid approach. Facial nerve function grade I was achieved immediately after the surgery in 79% with the middle fossa approach and 86% with the retrosigmoid approach. Long-term results showed normal facial nerve function in 87% versus 86% of the cases.

Conclusion: These results confirm our selection criteria for the surgical approach applied in acoustic neuroma surgery. More laterally localized tumors can be removed safely with the middle fossa approach with a fair chance of preserving residual hearing and good prospects of preserving facial nerve function. More medially localized tumors, and especially those compressing the brainstem, should be managed using the retrosigmoid approach which gives better control over the brainstem anatomy. Each individual case must be discussed between oto- and neurosurgeons on an interdisciplinary basis. Intraoperative monitoring is mandatory and valuable.